1. Field of the Invention
This invention relates to a display control integrated circuit (IC) for controlling display output onto a display and more particularly to a display control IC appropriate for display control on a display having an input panel.
2. Description of the Related Art
The art described in Japanese Patent Laid-Open No. Hei 2-188818 is known as a display control IC which controls display output onto a display having an input panel. FIG. 3 shows the configuration of such a conventional information processing apparatus, wherein numeral 20 is an input panel for input of handwriting; numeral 21 is a display such as a liquid crystal display panel; numeral 22 is a display memory which stores display data written by a CPU (central processing unit), etc.,; numeral 23 is a ROM (read-only memory) which stores read-only programs and data; numeral 24 is a RAM (random access memory) where programs and data can be written and read; numeral 25 is a CPU which controls the entire information processing unit; numeral 26 is I/O (input/output) control means for controlling a memory card 27; numeral 27 is a memory card which is removable storage means; numeral 30 is an input panel control LSI (large-scale integrated circuit) such as an analog-to-digital converter which converts input of the input panel 20 into input coordinates; and numeral 31 is a display control LSI which controls display on the display panel 21.
For an information processing apparatus having an input panel as described above, for example, to display an input path at positions on the display overlapping with input positions on the input panel as if the user drew an image directly onto the display screen with an input pen, the CPU reads input coordinate data of the input panel from the input panel control LSI, processes the data to obtain the display coordinates of the points to be displayed on the display, and writes the resultant display data through the display control LSI into the addresses of the display memory corresponding to the display coordinates.
Thus, according to the conventional art, both display control and input panel control LSIs are provided and the CPU controls them separately.
Recently, however, a portable information processing apparatus has been desired and to meet this demand, a small device which consumes low power is required. According to the above-mentioned conventional art, the CPU must perform display control in response to input coordinate data output by the input panel control LSI and may accordingly cause overload.